refactor(settings): drop two query keys nothing reads

The unit-system and glucose-unit selects invalidated
`userUnitPreference()` and `userGlucoseUnit()` after a save, but no
query was ever registered under either key; every surface reads the
units from the account payload, which both selects already refresh.

src/__tests__/baselines/version-stamp-comments.json

@@ -1,7 +1,7 @@
 {
   "$comment": "Comment lines that open with a release version, per file under src/. Maintained by src/__tests__/version-stamp-ratchet.test.ts.",
   "count": 2881,
-  "total": 9185,
+  "total": 9184,
   "entries": {
     "__tests__/account-payload-consumer-guard.test.ts": 2,
     "__tests__/acting-account-boundary-guard.test.ts": 7,
@@ -2691,7 +2691,7 @@
     "lib/queries/use-profile-claim.ts": 4,
     "lib/query-keys/admin.ts": 12,
     "lib/query-keys/ai-runs.ts": 1,
-    "lib/query-keys/auth.ts": 9,
+    "lib/query-keys/auth.ts": 8,
     "lib/query-keys/coach.ts": 13,
     "lib/query-keys/custom-metrics.ts": 1,
     "lib/query-keys/cycle.ts": 1,

src/components/settings/glucose-unit-select.tsx

@@ -29,9 +29,9 @@ import { resolveGlucoseUnit, type GlucoseUnit } from "@/lib/glucose";
  * locale.
  *
  * Persistence mirrors the unit-system select: a change PATCHes
- * `/api/auth/me/glucose-unit` immediately and invalidates `queryKeys.authMe()`
- * plus `queryKeys.userGlucoseUnit()`, so the dashboard tiles, the glucose
- * insight page and the targets panel re-render on the next /me refetch.
+ * `/api/auth/me/glucose-unit` immediately and invalidates `queryKeys.authMe()`,
+ * so the dashboard tiles and the glucose insight page re-render on the next
+ * /me refetch.
  */
 export function GlucoseUnitSelect({
   isAuthenticated,
@@ -66,9 +66,6 @@ export function GlucoseUnitSelect({
     onSuccess: () => {
       toastWrittenOutcome("success", t("settings.dashboard.glucoseUnit.saved"));
       queryClient.invalidateQueries({ queryKey: queryKeys.authMe() });
-      queryClient.invalidateQueries({
-        queryKey: queryKeys.userGlucoseUnit(),
-      });
       setOptimistic(null);
     },
     onError: (err) => {

src/components/settings/unit-preference-select.tsx

@@ -23,9 +23,8 @@ type UnitPreference = "metric" | "imperial";
  * picker rather than in a standalone card (it replaces the retired
  * `<UnitPreferenceCard>`). Persistence is unchanged: a change PATCHes
  * `/api/auth/me/unit-preference` immediately and invalidates
- * `queryKeys.authMe()` + `queryKeys.userUnitPreference()` so every chart
- * display transform (km/h vs mph, km vs mi) re-renders on the next /me
- * refetch — no manual reload, no contract change.
+ * `queryKeys.authMe()`, the account payload every chart display transform
+ * (km/h vs mph, km vs mi) reads, so they re-render on the next /me refetch.
  */
 export function UnitPreferenceSelect({
   isAuthenticated,
@@ -59,9 +58,6 @@ export function UnitPreferenceSelect({
     onSuccess: () => {
       toastWrittenOutcome("success", t("settings.dashboard.units.saved"));
       queryClient.invalidateQueries({ queryKey: queryKeys.authMe() });
-      queryClient.invalidateQueries({
-        queryKey: queryKeys.userUnitPreference(),
-      });
       setOptimistic(null);
     },
     onError: (err) => {

src/lib/query-keys/auth.ts

@@ -23,23 +23,6 @@ export const authKeys = {
    * settings/ai-section, targets/target-edit-sheet).
    */
   userThresholds: () => ["user", "thresholds"] as const,
-  /**
-   * v1.7.0 — Settings → Display metric/imperial control reads its
-   * current value from `GET /api/auth/me/unit-preference`. The PATCH
-   * mutation also invalidates `authMe()` so `useAuth().unitPreference`
-   * (and every chart display transform that keys off it) re-renders
-   * without a manual reload.
-   */
-  userUnitPreference: () => ["user", "unit-preference"] as const,
-  /**
-   * The mg/dL vs mmol/L glucose display control behind
-   * `GET /api/auth/me/glucose-unit`. A separate axis from the
-   * metric/imperial preference above — metric countries are split on
-   * which one they read glucose in — so it carries its own key. The
-   * PATCH also invalidates `authMe()`, since every glucose surface
-   * resolves the unit from the account payload rather than from here.
-   */
-  userGlucoseUnit: () => ["user", "glucose-unit"] as const,
 
   passkeys: () => ["passkeys"] as const,